The present invention pertains to detent mechanisms for use with fluid control valves and for releaseably restricting a valve spool of such a control valve against axial movement.
The purpose of such detent mechanisms is to provide means to releaseably secure the valve spool of a control valve in various axial operating positions and to restrict the valve spool against movement except when a force is applied to the valve spool by an operator to overcome the detent force. The valve spools referred to are of the type whic are axially movable within a control valve thereby varying fluid flow through the control valve by regulating the communication of various fluid ports within the control valve. A typical control valve and valve spool assembly may be operative to regulate fluid flow when the valve spool is in one of four different axial positions. The detent mechanism is intended to maintain the position of the valve spool when the operator has placed the spool in the desired position and to permit the operator to sense or feel a change in the axial position of the valve spool to permit him to control the operation of the valve without visual contact. That is, it is desirable that he be able to feel different forces on the control lever depending upon the position of the valve spool.
Some of the prior art detent mechanisms used in controlling the position of the valve spool comprise a somewhat complicated mechanical assembly including, for example, spring biased balls receivable in spaced indentations. Such prior art mechanisms have the advantage that they provide a means for permitting the operator to feel the position of the valve spool at its various operating positions. However, such devices are unduly complicated and expensive to manufacture and are generally subjected to rapid wear. Wear of these detent mechanisms generally causes the valve spool to misalign with the various valve ports and detracts from the operator's control of the valve. Furthermore, repair of such detent mechanisms results in complicated disassembly and reassembly procedures and special tooling. An additional drawback of such prior art detent mechanisms is that they prevent free and smooth axial movement of the valve spool between the detent positions and thus limit the throttling possible with the valve.